The programmable assembly of electronic equipment made from a plurality of electronic components has generated a need for adaptable feeder units which are ready to mount into existing work envelopes for use with pick and place machinery and robotic work stations. In a particular example, electronic component feeders used in the pick and place or robotic assembly of integrated circuit boards and like electronics applications must provide steady and dependable delivery of components to a given work site. It is also important that each component be delivered within a certain time frame and in the correct orientation so that each component can properly interface with the automatic pick and place or robotic machinery to ensure that the preset scheduling of an efficient production line is maintained.
One of the problems with many existing component feeders is their common inability to concurrently deliver several diverse components to the pickup machinery. Numerous current assembly processes are limited because many feeders can only feed one type of component at a time. This then requires a time-consuming series of sequential pickups of the different components by the pickup machinery, often from various different pick locations which results in a longer production time and hence, a much less efficient process.
Another problem with presently available component feeders is their common reliance on tube feeding. Typically, components are stored and shipped in tubes which are later mounted in a conventional component feeder for ultimate delivery to the pickup machinery. The dependence on these tubes often makes the existing feeders less efficient because the components will at times jam in the tubes or in the tube to feeder transition. This results in missed picks because either no component is delivered to the pick location or components are delivered in the wrong orientation or at the wrong time.
Yet another problem with many existing component feeders is that even without tube feeding, the components will often jam in their feeder delivery lanes. These lanes are often either too narrow or too large to allow for smooth passage of the respective components. When such a jam occurs, the assembly process must be stopped and the delivery lane cleared of the jammed components. Improperly sized delivery lanes can also cause the components to arrive misoriented at the pick location. The pickup machinery would thus pick up a component which would have to be reoriented, often manually, before it could be correctly placed in a circuit board thereby causing further interruption of the assembly cycle.
Jamming or misorientation of parts is also a problem with many feeders which rely on gravity to move the parts down to the pick location. Gravity feed problems usually occur when large quantities of components are stacked behind the lead component. The components stacked behind the lead component present a cumulative weight which presses down on the lead component. The larger the cumulative weight, the greater the force which is present to push the lead part into its nest structure at the pickup location. This cumulative weight force will also be referred to as a "back pressure" force. This "back pressure" force often coacts with the inherent frictional characteristics of the nest structure to hold the lead component therein frictionally and, of course, the greater the "back pressure" force, the greater the frictional force holding the part in the nest structure to resist the lifting force of the pick and place machine when it attempts to lift the part from the nest.
A still further problem that is endemic to many existing belt feeders is that they use a continuous belt motion during operation. A continuously moving belt is undesirable because it continuously grinds on the components, particularly when these delicate components are held immobile at the pick point location waiting to be retrieved by the pickup machinery. Even though the component is stationary, the component pins usually remain in contact with the moving belt which may then wear away the plating on the pins and/or may also grind against other important architectural features of the component.
The above problems generally result in lost manufacturing capacity, higher rejection rates and greater attendant costs due to damaged components, and/or ultimately, excessive assembly downtime. Therefore, there exists a need for improved, efficient belt component feeders for the manufacturing of electronic assemblies. Such component feeders should consistently provide stable, non-continuous, non-abrasive delivery of a variety of multiple components to preselected pick locations within the proper time frame and in the proper orientation. It is toward these goals that the present invention is directed.